1. Field of the Invention
The present invention relates to a head suspension for a disk drive incorporated in an information processing apparatus such as a personal computer, and particularly, to a head suspension having a piezoelectric element that is attached thereto with a nonconductive adhesive and deforms in response to an applied voltage.
2. Description of Related Art
Small-sized, precision information devices are rapidly advancing, and for use with such devices, needs for micro-actuators capable of conducting positioning control for very small distances are increasing. Such micro-actuators are highly needed by, for example, optical systems for correcting focuses and inclination angles, ink jet printers for controlling ink heads, and magnetic disk drives for controlling magnetic heads.
The magnetic disk drives are strongly expected to increase their storage capacities. Increasing the storage capacity of a magnetic disk drive is achievable by increasing the storage capacity of each magnetic disk in the magnetic disk drive. The storage capacity or recording density of a magnetic disk will increase, without changing the diameter thereof, if the number of tracks per inch (TPI) on the magnetic disk increases, i.e., if the width of a track narrows. For this, a magnetic head of a head suspension installed in the magnetic disk drive must conduct a precise positioning operation in a direction across the tracks, i.e., a sway direction. For realizing the precise positioning operation, an actuator capable of accurately moving and positioning the magnetic head in a very small section is needed.
To meet the need, a head suspension for a disk drive has been proposed in Japanese Unexamined Patent Application Publication No. 2002-184140. The head suspension includes a base plate, a connection plate having a hinge thinner than the base plate, a load beam provided with a flexure, and a piezoelectric actuator having a pair of piezoelectric elements.
This related art employs a dual actuator system that involves, for a precise positioning purpose, a voice coil motor and the piezoelectric actuator having two piezoelectric elements made of, for example, PZT (lead zirconate titanate).
The piezoelectric actuator in the dual actuator system minutely moves a front end of the load beam in a widthwise direction (sway direction) of the head suspension. Compared with a single actuator system employing only the voice coil motor, the dual actuator system is capable of more precisely positioning a magnetic head attached to a front end of the head suspension.
An important issue for the head suspension employing the dual actuator system is to protect the brittle piezoelectric elements from damage and secure electric insulation between the head suspension body and the piezoelectric elements.
One approach to address the issue is disclosed in Japanese Unexamined Patent Application Publication No. 2002-184139. This related art is a head suspension for a disk drive, having an actuator base and a piezoelectric element. The piezoelectric element is attached with a nonconductive adhesive to an opening formed in the actuator base. The adhesive covers a circumferential end face of the piezoelectric element.
This related art is capable of protecting the piezoelectric element from being damaged, preventing particles from dropping off the surface of the piezoelectric element, and securing insulation between the piezoelectric element and the actuator base.
The related art, however, has a possibility of, when attaching the piezoelectric element to the opening, oozing the nonconductive adhesive out of the periphery of the opening and spoiling the vicinities of the opening.